On known wrapping wheels, particularly for stacks of sweets, operating according to the above method, the two lateral flaps are normally folded together to form the longitudinal rib by a gripper on the relative radial seat, and are fed, so folded, to a sealing station where two opposite sealing devices grip the rib; the rib is released when the radial seat is started up again and leaves the sealing station; and the rib is folded squarely by a fixed folding member downstream from the sealing station.
In other words, the longitudinal rib is sealed during a stop of the relative radial seat at a sealing station, and so affects the output rate of the wrapping wheel as a whole. That is, sealing the longitudinal rib takes a relatively long time, normally longer than the follow-up folding and sealing operations performed by the wrapping wheel at other work stations, so that the stop times of the wrapping wheel must conform with those of the longest operation, thus reducing efficiency.